Project Summary Our goal is to develop VTC-G90 as a novel tolerance-inducing therapeutic to treat Graves? Disease (GD). GD is an autoimmune disease in which patients produce an antibody that binds to the thyroid stimulating hormone receptor (TSHR), mimicking the effects of thyroid stimulating hormone (TSH)2. Autoimmune-induced hyperthyroidism is induced, resulting in a wide range of symptoms such as thyroid enlargement (goiter), muscle weakness, atrial fibrillation due to increased heart rate leading to stroke, and blindness due to progressive Graves? opthalmopathy2, 3 For successful induction of immune tolerance, mucosal tissues play a significant role27-29. The epithelial layers that cover the Gut Associated Lymphoid Tissue (GALT) and Nasopharyngeal Associated Lymphoid Tissue (NALT) areas contain a subpopulation of specialized cells (microfold or M cells) that sample environmental antigens and present them to the adjacent immune cells30, 31. Several studies now confirm these cells play a crucial role in the generation of tolerance to a given antigen5, 32-34. Reoviruses are segmented, double-stranded RNA viruses that bind and infect humans via mucosal surfaces using the viral coat protein, p?135, 36. We have demonstrated that fusion proteins, consisting of p?1 fused to an antigen of choice, can bind to M cells and generate a tolerogenic immune response to that antigen4, 5, 32-34. The ability of p?1-antigen targeting to induce tolerance has been studied in both allergy and autoimmune models, using both oral and intranasal dosing routes4, 5, 24, 32. For instance, p?1-mediated tolerance to the MS auto- antigen, MOG, but not recombinant MOG alone, prevents CNS pathology and clinical manifestation of experimental autoimmune encephalitis (EAE) in mice. The tolerance response is antigen specific, and is due to the induction of anti-inflammatory cytokines and an increase in suppressive regulatory T cells (Tregs) and regulatory B cells (Bregs) 4, 5, 24, 32 The goal of this Fast-track SBIR application is to develop VTC-G90 as an orally administered, tolerance therapeutic for the treatment of GD. VTC-G90 is a recombinant protein consisting of p?1 fused to the antigenic region of TSHR. This design allows VTC-G90 to exploit p?1 targeting of the auto-antigen specifically to M cells, and to induce tolerance to the known antigenic region of the TSHR. Successful completion of this proposal will create a first-in-class tolerance therapeutic for newly diagnosed GD patients. The high-level objectives are to: 1) establish VTC-G90 production and analytical assays to support manufacturing, purification, bioactivity determination, and formulation; 2) define the IND-enabling studies to support our clinical study design, and 3) develop non-GLP and GLP preclinical datasets to help us obtain FDA IND approval. Successful commercialization of VTC-G90 would ultimately provide a profound front-line medical advancement in the treatment of GD.